//-----------------------------------------------------------------------------
// MurmurHash3 was written by Austin Appleby, and is placed in the public
// domain. The author hereby disclaims copyright to this source code.

// Note - The x86 and x64 versions do _not_ produce the same results, as the
// algorithms are optimized for their respective platforms. You can still
// compile and run any of them on any platform, but your performance with the
// non-native version will be less than optimal.

#include "../lib/murmur3_hash.h"
#include "../lib/hash.h"

//-----------------------------------------------------------------------------
// Platform-specific functions and macros

// Microsoft Visual Studio

#if defined(_MSC_VER)

#define FORCE_INLINE    __forceinline

#include <stdlib.h>

#define ROTL32(x,y)    _rotl(x,y)

#define BIG_CONSTANT(x) (x)

// Other compilers

#else    // defined(_MSC_VER)

#define    FORCE_INLINE inline __attribute__((always_inline))

static inline uint32_t rotl32 ( uint32_t x, int8_t r )
{
    return (x << r ) | ( x >> ( 32 - r ) );
}

#define    ROTL32(x,y)    rotl32(x,y)

#define BIG_CONSTANT(x) (x##LLU)

#endif // !defined(_MSC_VER)

//-----------------------------------------------------------------------------
// Block read - if your platform needs to do endian-swapping or can only
// handle aligned reads, do the conversion here

static FORCE_INLINE uint32_t getblock32 ( const uint32_t * p, int i )
{
    return p[i];
}

//-----------------------------------------------------------------------------
// Finalization mix - force all bits of a hash block to avalanche

static FORCE_INLINE uint32_t fmix32 ( uint32_t h )
{
    h ^= h >> 16;
    h *= 0x85ebca6b;
    h ^= h >> 13;
    h *= 0xc2b2ae35;
    h ^= h >> 16;

    return h;
}

//-----------------------------------------------------------------------------

/* Definition modified slightly from the public domain interface (no seed +
 * return value */
uint32_t MurmurHash3_x86_32 ( const void * key, size_t length )
{
    const uint8_t * data = ( const uint8_t* ) key;
    const int nblocks = length / 4;

    uint32_t h1 = 0;

    uint32_t c1 = 0xcc9e2d51;
    uint32_t c2 = 0x1b873593;

    //----------
    // body

    const uint32_t * blocks = ( const uint32_t * ) ( data + nblocks * 4 );

    for ( int i = - nblocks; i; i ++ )
    {
        uint32_t k1 = getblock32 (blocks, i);

        k1 *= c1;
        k1 = ROTL32 (k1, 15);
        k1 *= c2;

        h1 ^= k1;
        h1 = ROTL32 (h1, 13);
        h1 = h1 * 5 + 0xe6546b64;
    }

    //----------
    // tail

    const uint8_t * tail = ( const uint8_t* ) ( data + nblocks * 4 );

    uint32_t k1 = 0;

    switch ( length & 3 )
    {
        case 3: k1 ^= tail[2] << 16;
        case 2: k1 ^= tail[1] << 8;
        case 1: k1 ^= tail[0];
            k1 *= c1;
            k1 = ROTL32 (k1, 15);
            k1 *= c2;
            h1 ^= k1;
    };

    //----------
    // finalization

    h1 ^= length;

    h1 = fmix32 (h1);

    //*(uint32_t*)out = h1;
    return h1;
}

